Instrument barrel



FIG. 1 is a perspective view of my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof; and,

FIG. 4 is a right side view thereof, the left side view being a mirror image; and,

FIG. 5 is a top view thereof.

The stipple-like pattern shown on the clip and globe and the dashed lines shown on the lower portion of the instrument barrel in FIGS. 1, 4, and 5 illustrate environmental matter, which form no part of the claimed design. 

The ornamental design for an instrument barrel, as shown and described. 